Process of concentrating ores.



E. GAYFORD L G. CRERAR.

PROCESS 0F CONCENTRATING CRES. APPLicATloN ,mm MAY 29, 1 914.

TAIL/NGS BALL MIL L 3% www? claim.

UNITED sTATEs PATENT oEErcE,

EENEsT GAYEOBE AND GEORGE CEERAE, OE sALT LAKE CITY, UTAH, AssIeNoEs To METALS RECOVERY COMPANY, OE AUGUSTA, MAINE, A COnPOEATI'oN OE MAINE.

IROCIESS 0F CONCENTRATING DRES.

.Specification of Letters P atent.

Patented Mar. 21, 1916.

Application led May 29, 1914. Serial No. 841,710.

lTo all whom t may concern.'

Be it known that we, ERNEST GAYEORD,

a subject of the King of Great Britain, andores by separating the metallic particles from the barren or rocky constituents thereof, and the invention consists of the process which we will hereinafter describe and Our process-is specically related tothe art commonly known as flotation processesV and which is distinct from the usual gravity concentration processes, in which the particles are separated by theirv dilierences in weight, or specific gravity, in that in the flotation process a Acertain percentage of oil, or of two dissimilar oils, or an oil and an acid, or an Oil and an alkali, is mixed with nely ground ore pulp and the mixture is then subjected to a violent agitation with the result that large volumes of air are beaten into, impregnated or entrained by the pulp for the purpose of producing a froth composed of bubbles of airv and oil to which the mineral particles attach, said froth having the appearance of an aggregation 0r mass of ine soap bubbles which when collected and the froth discharged or broken down, by natural settlement, by suction or vacuum, or by the addition of cold water, or other means, displaces the mineral particles that have been caught'.

In the accompanying drawing we have illustrated diagrammatically, an apparatus capable of working our process and wherein the several parts of the apparatus are so arranged as to perform the process progressively or in a ste -by-step manner.

In carrying out our process we first reduce the mineral-bearing. material by some suitable mechanism and which may include an -ore Crusher, or a reducing mill, A, of any appropriate character, and in which mill the ore is reduced or crushed'to a desired size, say such that it will pass through the meshes of a One-half inch screen, the crushing being, preferably, done with the` ore in a dry 'con'- dition. After being crushed or reduced to the desired size, and an adequate amount of water and the necessary amount of oil,

-an oil and acid, or oilv and an alkali, or material or substance having the property of produclng a suitable froth with the ore is .mixed with the pulp and the mixture fed Into armachine where it is wet ground or otherwise treated to further reduce the size of the particles. This second machine may, for instance, be represented by the well known ball-mill, B, which will reduce the material so that it will pass a screen having meshes about 10 tothe lineal inch, said mill having an inlet at one end to receive the material from the first grinding or reducing machine and having an outlet at the opposite end` for the discharge of the ground material therefrom. While we have shown and described a ball-mill as being suitable for the above purpose, it will be understood that any standard machine capable of crushing or reducing the material may be substi tuted lfor the ball-mill without departing fromthe spirit of our invention.

Associated in proper relation with a discharge of the ball-mill 'or reducing machine, B, is a frothing iotation machine, C, of suitable character. A machine well adapted for this step of our process includes a tank having an inclined bottom provided with one or more air cells, D, above which and forming the topof the same is a porous floor, E, through'which air, gas, or vapor admitted under pressure into said cells will be discharged in a number of infinitely line streams into the body of pulp in the tank with the result that a froth, foam or suds is generated andwhich froth, foam or suds rises to the surface of the contents of the tank and is delivered through an overflow lip or discharge, F, and finally is sent as a concentrate to a cleaning machine or bin. This frothing flotation machine, which we have illustrated in connection with our process forms no essential part of the presbecauseof the inclination of the said floor they are caused to gravitate thereover to a duction of the material.

discharge, G. The machine, therefore, floats a concentrate and discharges a tailings 1n, 'Water'.

Succeeding the frothing fiotation machine is another reducing machine, .-H, which may be of any suitable character, as a pebble-mill capable of reducing the material so that it will pass a screen of aboutO mesh per square inch. However, the character of this reducing machine is unimportant, provided it has the capacity to further reduce theore, and the machine shown may be regarded as but representative of any mill or crushing apparatus suitable for the 'reducticn of the tailings delivered from the prel ceding frothing flotation machine, C.

In' introducing the tailings from the i frothing flotation machine, C, into the aforesaid second reducing mill, H, for further 4reduction, We maycalso add to the tailings and its supply of Water, a further amount of a suitable frothing agent, so that the further reduction of the ore, and which ore represents the tailings-from the preceding frothing flotation machine, C, is done in the presence of a fresh supply of a suitable frothproducing agent, and there is thus the intimate admixture of this agent With the pulp during the further regrinding or further re- Succeeding the second reduction'mill, H, is another rothing flotation machine, I, of a character similar to the one before described, or of any other suitable character and in this machine a froth, foam or suds is produced in the manner similar to that before described, and theconcentrates are caused to overflow or pass from this machine to the cleaning machine or bin or other depository. This machine, I, therefore, fioats a concentrates and discharges a tailings in water, to which tailings a further amount of a suitable frothing agent, as before described, is added, if desired, andthe tailings further reduced in size, if this is found to be desirable by recrushing orfurther grinding in any standard machine, say a pebble-mill until the parti`cles may pass a screen of say aboutA 80 mesh. Thus, the material discharged lfrom the reduction mill, H, is sent direct to a frothing flotation machine which in turn lioats a concentrate, which is liberated by the recrushing, and discharges a tailings which in ,turn is reduced to a smaller lsize and sent toa frothing flotation-machine and therein subjected to the action of the froth- 4ing agent, andthe air, gas or vapordelivered into the same through the porous fioor or bottom, as before described. These several operations are carried out -until the point is reached when the recrushng and reoating steps do not recover. suilicient mineral to make them profitable, the finalflotation machine discharging a tailings-which has but little, if any, value.

From the foregoing, it will be understood that our process involves ycrushing or reducing mineral-bearing material, by steps, to

suitable sizes, and Hoating the liberated min-y eral at each crushing step, the number of the steps and the fineness of the crushing being dependent upon the nature of the ore.v

The results which we obtain from theI practice of the foregoing process are superior to those which .occur when the ore is crushed at once to the final size and then treated by flotation, as it is a well known axiom in oreptreatment, that the metal losses occur in the impalpable line mineral made in crushing the ore and the ner the crushingv the larger the amount of such impalpable mineral, therefore, in our step flotation,

the mineral liberated at each crushing is floated before thenext stepor before it is again subjected to a further and final reduction, which would reduce such mineral to an undesirable condition were it nct'removed as soon as it is liberated from the gangue.

In all mineral-bearing material a portion of the mineral is liberated'l when the crushing is comparatively coarse, Whereas some 1s lnot liberated until ythe reduction is comparatively fine. We arel aware that stepcrushing has been resorted to in ore dressing and We do notclaim the same broadly as our invention, but step crushing combined With step flotation has never been practised, as far asWe know, and that portion of our process which involves the floating of the concentrates of each crushing step 'crushing machine at each step; no complicated machinery is required, simply a crushing machine and a flotation machine for each step.

Having thus described our invention what We claim 'as new and desire to secure by Let- 1. The p-rocess herein described, consisting, essentially, in progressively reducing, by Successive stages, ore mixedwith water and a frothable agent 'having a preferential affinityA for metalliferous matter, aerating the mixture resulting from each reduction,

and floating ofi' the concentrates liberated at each reduction. s

2. The process herein described which consists, essentially, in progressively reducing at intervals-ore mixed with Water and an oily agent having a preferential aliinity for 'metalliferous matter, and aerating the mixture between successive reductions and 1 floating oif the concentrates liberated during a preceding reduction; y f

3. The process herein described which consists, essentially, in crushing ore mixed with Water and a frothable agent having a preferential aiiinity for metalliferous matter, then aerating the mixture to buoy up and float ot the concentrates liberated during the crushing, then further reducing the remaining tailings and aerating the mixture to buoy up and float off the concentrates liberated during the second reduction.

4. The ore concentrating process described herein Which consists, essentially, in the step by step reduction of ore mixed lWith water and a, frothable agent having a preferential 4ainity for metalliferous mat- 15 ter, aerating the mixture following each step of the reduction and floating off the concentrates liberated at each reduction and previous to a succeeding reduction.

In testimony whereof we aix our signa- 20 tures in presence of two Witnesses.

ERNEST GAYFORD.

GEORGE CRERAR. Witnesses:

GEO. W. LUCAS, J. M. CALLoIs. 

